Underground Concrete Rainwater Tank

rampantbunny

I'm starting a domestic build (some self build\some direct labour) at some point before the end of year. I'm considering building an underground concrete tank for rainwater harvesting while having my groundworks done. A plastic tank won't fit the bill as the walls of the tank will serve as a retaining wall for a drop in levels at rear boundary of site (without the tank, I'd still need to get shuttering to build a retaining wall, so may as well build 4 walls of a tank while I'm at it).


The water table is quite high where I'm building but even then only about a foot of the tank will be below this level.
The question I have is, if I make the tank out of poured reinforced concrete, how do I waterproof this? A paint on solution, glass fibre products, an additive to the concrete mix etc?

cullym

I've found some good information here

http://www.agriculture.gov.ie/farmerschemespayments/farmbuildings/farmbuildingandstructuresspecificationspdfformat/

Look at spec S171 for rainwater harvesting and you'll see refs to other specs for tank construction, concrete specs etc.

hexosan

What size is the tank your looking to install. I've just completed waterproofing a domestic basement on my self build. If you want to PM I've looked at a ton of waterproofing options and have prices from most the major products. Doubt I can name them there.

rampantbunny

cullym wrote: »

I've found some good information here

http://www.agriculture.gov.ie/farmerschemespayments/farmbuildings/farmbuildingandstructuresspecificationspdfformat/

Look at spec S171 for rainwater harvesting and you'll see refs to other specs for tank construction, concrete specs etc.

Cheers cullym. Never would have thought to look there. I'll re-read over the information you linked to but at first glance I didn't see anything about waterproofing the tanks, but still good info. on the concrete requirement and some filter information too.

rampantbunny

hexosan wrote: »

What size is the tank your looking to install. I've just completed waterproofing a domestic basement on my self build. If you want to PM I've looked at a ton of waterproofing options and have prices from most the major products. Doubt I can name them there.

PM sent hexosan.
Haven't any firm plans for the size of the tank I want to install yet. Will firm that up when I see what sort of prices I'm looking at for waterproofing.

etcetc

@hexosan can you forward on that pm to me also

cullym

@rampantbunny I'm just coming back round to looking at this now for my own needs, did you make any progress with this.

rampantbunny

cullym wrote: »

@rampantbunny I'm just coming back round to looking at this now for my own needs, did you make any progress with this.

I built a tank. Pretty massive (too big for my domestic water needs but there are other uses for it).

I ordered concrete and specified that a mixture be added to waterproof the product. Contains fibres and looks the part at least. 250mm of concrete in the walls and even more in the base...but because the fella working the concrete doesn't believe in using a poker, there is still a small leak. For the price I paid I'm still well happy though.

cullym

@rampantbunny, thanks for the reply. Could you let me know what admix you used? If you can't post on here can you PM me please?

Thanks

cullym